Design Near-threshold Photoelectron Imaging Spectrometer Based on UV Laser Induced Photoelectron Emission Anion Source (cited: 2)

We have developed a compact photoelectron imaging facility, including an anion source with dissociative photoelectron attachment to molecules, a linear time-of-flight mass spec-trometry (TOFMS), and an orthogonal high-resolution threshold photoelectron velocity mapimaging spectrometer (VMI). Intense and cold cluster anions were prepared in photoelectron-attachment processes upon pulsed UV laser ablation of metal target. Combining this anion source with TOFMS-VMI, the achieved mass resolution is about 200, and the electron ki-netic energy resolution is better than 3%, i.e., 30 meV for 1 eV electrons. More importantly, low-energy photoelectron imaging spectra for CH₃S^- and S₂^- at 611.46 nm are obtained. In both cases, the refined electron a±nities are determined to be 1.8626±0.0020 eV for CH₃S and 1.6744§±0.0035 eV for S₂, respectively. Preliminary results suggest that the apparatus is a powerful tool for estimating precise electron affinities values from threshold photoelectron imaging spectroscopy